I think that a remake will be made eventually. While people can use the argument that it isn't needed since people can technically get all of the pokemon already, there are other reasons. The main reason is of course, money. While I love Nintendo dearly, they love money more than anything - which is fine, but it's the truth. As many have said previously, this is why they make three different versions of the same game, basically - they don't have to do it, but they do it for the money.
A Johto remake would make them quite a bit of money, because the younger audience who never played the games would want to try them out, while the older audience will probably enjoy it for the nostalgic factor and because it's a new pokemon game, simply. I know many people can argue that other generations were better than the 2nd one, but it was an incredibly popular generation, and had many different, unique things in it that are still unique to the games, despite newer generations coming out. I think it was one of the most important generations for implementing so many fun things - day/night, events on certain days, and much more.
I have no idea if they will include Kanto in the Johto remake, because it might be pointless considering the remake of the first generation already. As much as I loved that idea, it was primarily in there for filler, and it was incredibly easy - hopefully if Kanto is added into the remake, they'll make it more interesting. I'd love to see Johto expanded upon more, though.
Anyway, I think there will be a remake. It might take a while, but eventually it will happen, since it's easier to remake an incredibly popular game than to design a completely new region, with a new story line, geography, etc. I'm hoping the remake will come out after the 5th generation similar to how the FR/LG games came out after R/S, and that seems the most logical way it'll be released. We might have to wait a while, but I'm quite sure it'll happen. :)